Exactly. Plus, creating your own "audible" comfort zone, is very tricky. A given sound that some people like, e.g. frogs in a nature soundscape, can be the sound other dislike, or are even afraid of. Offering level control over every audible elements in a soundscape is very important, and not available on YouTube.

It no doubt lacks the customization, but the overwhelming variety of options makes it likely that most people will find something to their liking. YMMV, of course.

Personally I've used everything from Japanese-themed Lo-Fi to Skyrim soundtracks to nature sound to Starship Enterprise warp core background noise.